Can't change test case name in report pytest report

Question

I can't change the test case names in the html report Based on this I have the following code in my conftest file:

    @pytest.mark.hookwrapper
def pytest_runtest_makereport(item, call):
    outcome = yield
    report = outcome.get_result()
    test_fn = item.obj
    docstring = getattr(test_fn, '__doc__')
    if docstring:
        report.nodeid = docstring

@pytest.mark.optionalhook
def pytest_html_results_table_row(report, cells):
    for cell in cells:
        if cell.attr.class_ == "col-name":
            if hasattr(report, "docstring"):
                cell[0] = report.docstring
            break

And the following code in a test case:

 def test_demo_server(self):
        self.test_demo_server.__doc__ = "TEST"

I get the following error: AttributeError: attribute 'doc' of 'method' objects is not writable

I'm not sure how to proceed from here.